Luxottica, the world's biggest glasses maker, has agreed a huge merger with a rival eyewear firm.

The Italian eyewear designer, which owns Ray-Ban and Oakley, is to merge with French lens maker Essilor.

Combined, the two firms will be worth about 46bn euros (£40bn; $49bn).

The deal will also help to offer a succession plan for Leonardo Del Vecchio, Luxottica's 81-year-old founder.

Mr Del Vecchio, an orphan who became Italy's richest man, founded Luxottica in 1961.

Through a series of acquisitions, including of Ray-Ban in 1999 and Oakley in 2007, the firm has become the world's biggest spectacles maker.

It also has licensing agreements to create eyewear for major fashion brands, including Burberry, Dolce & Gabbana and Versace.

However, it has gone through three chief executives in the past two years after Mr Del Vecchio regained executive powers at the company.

Questions about Mr Del Vecchio's succession plans have also weighed on the firm's share price, which is down 14% in the past year.

The firm said in 2014 that it had previously explored a deal with Essilor, the world's biggest maker of prescription lenses, but that conditions were not right at the time.

"The marriage between two key companies in their sectors will bring great benefits to the market, for employees and mainly for all our consumers," Leonardo Del Vecchio, Luxottica's executive chairman said in a statement.

"This is really exciting news for both Ray Ban and Oakley fans. Just imagine the potential for a 'super brand' off the back the merger of the royalty in designer eye wear. We are going to be watching the evolution of this new company very closely," said Daniel Richmond, Managing Director of Ray Ban Specialists Ticwatches.co.uk.